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EXTENSION NOTES: Lawns, gardens need water

The last several weeks have been very dry for most of the Tri-State. While annuals are a little wilted, most established garden plants aren’t suffering…yet. To keep our plants stress-free, we should begin irrigation now.

EXTENSION NOTES: Lawns, gardens need water

The last several weeks have been very dry for most of the Tri-State. While annuals are a little wilted, most established garden plants aren’t suffering…yet. To keep our plants stress-free, we should begin irrigation now.

Almost everything in the southern Indiana garden, except for known drought-tolerant plants, should receive the equivalent of one inch of water per week. I’ve seen many confused expressions when I say this. So let me explain what this means. If you set out a rain gauge, coffee can, pickle jar or anything with straight sides, you can capture the rain (or sprinkler water). The side of the rain gauge will show how many inches of rain we had. For the coffee can/pickle jar, just stick a ruler in the container and see how far up the ruler the captured water goes. When you hit one inch, you’ve done enough.

If you are watering a raised bed by hand or carrying water out to community garden in jugs, how can you tell if you’ve added enough water? First, you need to know that one inch of rain equals one-half gallon of water per square foot of garden.

Measure the length and width of your garden bed, and multiply those two numbers together. That number equals the total square feet of garden that must be watered. Let’s say, for example, that you have a standard raised bed that’s 8 feet long and 4 feet wide. That equals 32 square feet of bed. One-half gallon of water per square foot, times 32 square feet, equals 16 gallons of water.

What if you’re watering by hand? You can’t measure inches of rainfall with a hand-held hose. And you’re not filling (and counting) gallon jugs. Therefore, you need to time yourself.

Get a 5-gallon bucket, and hook up your hose with whatever spray head you like to use. Using a watch, time how long it takes to fill the bucket, using the same pressure and spray head setting you would use in the garden. Let’s say, for example, it takes two minutes (120 seconds) to fill that 5-gallon bucket.

In our above-raised bed, we calculated we needed 16 gallons of water to adequately irrigate the bed. That’s slightly more than three full buckets of water. If each 5-gallon bucket takes two minutes to fill, and we need three buckets worth, that’s six minutes of watering per bed. Actually, six and a half minutes, but I won’t quibble.

A final way to irrigate is to use a soaker hose. This is a length of hose that has tiny holes poked in it. Water oozes slowly out of the hose, and drips directly onto the soil. Your goal is to get moisture down to a depth of six to eight inches deep in the soil. How long this takes depends on your soil type, water pressure and brand of hose you bought. To figure this out, dig down into the soil next to the hose every hour or so, and see how deep the moisture has gone. If it takes three hours to soak the soil deeply enough, then you can set up an alarm or even hook up a timer to your faucet and water that way.

We’ll talk more about watering next week.

Larry Caplan is an extension educator-horticulture with the Purdue University Cooperative Extension Service, Vanderburgh County/Southwestern Indiana. You can send email to him at LCaplan@purdue.edu.